Jack and Jill were, well Jack anyways, the more interesting characters from the first book. Reading about what happened to them in the Moors was honestly really sad. They have some really shitty parents that's for sure. 

In a lot of ways, this was more Jack's book than Jill's. The Moors sounds like an unpleasant but fascinating place. I would love to learn more about what lies beyond that door more. 

Jill, in a lot of ways, was a the more pliable person and more easily fell under "The Master's" spell. She either wasn't willing to, or didn't care about the darker side of him. 

I do find it interesting that most of  the girls at the school assumed that it was Jack who got  them kicked out of their door. I wonder if it had anything to do with Jill being more typically 'feminine'. They also  never seemed to ask who Jill's "Master" was.   

I hope this isn't the only book where we see the kids before they go through the door. Having the context of what drew them to a door is as interesting as what's behind the doors. A couple of the kids at Eleanor's school seemed to come from a pretty healthy households.  Jack and Jill didn't so a door  opening for them made  a lot of  sense, even if the land that opened to them wouldn't be most people's idea of a good place. It was just a place that allowed them to learn who they are.

I kind of want to know what happened to the girls after they go back at the end of Every Heart. I think one of the later books is about that, I have the first five books  in this series, and I look forward to reading it. Seanan McGuire is becoming  a favorite author, I plan to read more of her books soon.